Much online content is made available through web sites or web syndication feeds. RSS (“Really Simple Syndication”) and Atom are popular web feed formats used to publish frequently updated works in a standardized format. A typical content feed document includes full or summarized text, plus metadata such as publishing dates, authorship, etc. Internet users can subscribe to desired contents through these feeds. Additionally, internet users often use online bookmarking services to keep a reference to their favorite contents on the web.